As examples of methods for controlling plant diseases and pests, mention may be made of physical control methods and field husbandry control methods which employ crop rotation or solar heating, chemical control methods using agrichemicals, control methods utilizing disease-resistant varieties, biological control methods using attenuated viruses or antagonistic microorganisms on pathogenic fungi, and the like. Among these methods, research and development for agrichemicals and particularly organo-synthetic fungicides have been significantly improved in recent years, and many agents having high potency and exhibiting various effects are continuously being developed. Furthermore, various application methods have also been provided. The chemical control methods using these have greatly contributed to controlling plant diseases, saving labor in controlling operations, and the like, and have been widely employed. However, recently, it is observed in some crop plants and diseases that controlling effects provided by chemical control methods are reduced due to the appearance of so-called chemical-resistant pests, and this has become a problem. In addition, as a result of continuous cropping forced by spreading of monocultures, outbreaks of infectious diseases via soil, which are believed to be difficult to control with agrichemicals, have become a serious problem in various locations. Furthermore, in methods in which large amounts of agrichemicals are repeatedly employed, chemical substances, which are not naturally present, are released into the environment. For this reason, it has been understood that not only chemicals which are directly toxic to animals and plants, but also non-toxic chemicals, can cause adverse effects on the environment.
As described above, the control of diseases with agrichemicals is highly likely to reduce controlling effects due to the appearance of resistant pests. In this case, it is necessary to develop new fungicides. In addition, with respect to controlling diseases which are believed to be difficult to control with agrichemicals, alternative means or means used together with other methods must be implemented. In addition, it is desired that a control technique which is safer in view of the environment be established.
Recently, in light of these circumstances, controlling methods depending on the use of agrichemicals are being reconsidered, and biological control methods utilizing microorganisms (so-called biological control agents) which are believed to be safer for the environment compared with agrichemicals have been proposed, and some of these have been put to practical use.
In research for biological control of plant diseases, utilization of attenuated viruses, utilization of attenuated pathogenic or non-pathogenic type microorganisms of pathogenic microbes, utilization of antagonistic microorganisms, and the like, have been attempted. Among these, there is much research on utilization of antagonistic microorganisms. In addition, there are many reports on research for controlling diseases among the antagonistic microorganisms in the genus Bacillus. However, the genus Bacillus has not been found to exhibit effects for controlling a broad spectrum of diseases.